The first PRIMO Symposium was held in Plymouth, UK in 1981 with the goal of stimulating international scientific interactions in aquatic toxicology. The success of the first PRIMO meeting led to a second in 1983 in Woods Hole, USA and then to biennial meetings worldwide. Although the word 'marine' was used to produce the meeting acronym, the meeting has never distinguished between, and has always included, marine and freshwater organisms and research. The PRIMO conference series has always been committed to disseminating scientific and research progress through the publication of special issues in two international scientific journals, Aquatic Toxicology and Marine Environmental Research. Furthermore, and maybe most important, the PRIMO conference series is committed to encouraging the participation and recruitment of young researchers in the field through provision of travel grants and reduced conference fees for students.